Keywords

Abstract

Carbon nanotube field-effect transistors (CNTFETs) with
local electrolyte gated in solution provided high
performance in terms of subthreshold slope and
transconductance, resulting from the modulation of the
conduction in the carbon nanotube channel and the large
gate capacitance. Using the CNTFETs, label-free protein
biosensors have been fabricated to detect immunoglobulin
E (IgE), in which CNT channels were modified with
aptamers. Since aptamers are artificial oligonucleotides,
the aptamers are smaller in size than the Debye length.
Therefore, the biosensors are expected to detect IgE with
high sensitivity. After the 5’- amino modified aptamers
were covalently immobilized on the CNT channels, the
electrical properties of the CNTFETs were monitored in
real time. The introduction of target IgE at various
concentrations caused a sharp decrease in the source-drain
current and gradual saturation at lower values. From
electrical measurements in IgE concentration dependent,
the association constant between IgE molecules and IgE
aptamer could be calucated to be 5.14 × 108
(M-1
) using
the Langmuir adsorption isotherm.